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arxiv: 2605.18664 · v1 · pith:X4Y2FEOGnew · submitted 2026-05-18 · ⚛️ physics.atom-ph

Switching Rydberg interactions by three orders of magnitude using a terahertz field

Karen Wadenpfuhl , Aaron Reinhard , Oliver Hughes , Lucy Downes , Kevin Weatherill , C. Stuart Adams This is my paper

Pith reviewed 2026-05-20 01:36 UTC · model grok-4.3

classification ⚛️ physics.atom-ph
keywords Rydberg atomsterahertz fieldinteraction switchingphoton storageRydberg interactionsquantum computingquantum opticsatom-atom interactions
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The pith

A pulsed terahertz field switches Rydberg atom interactions by three orders of magnitude.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

The paper shows how a pulsed terahertz field can be used to turn the strength of interactions between Rydberg atoms up or down by a factor of one thousand on a fast timescale. Rydberg atoms interact strongly when excited to high-lying states, but earlier methods using microwave fields could only reach states with similar energies and thus offered limited switching range. Terahertz pulses connect states whose principal quantum numbers differ enough to change the interaction coefficient dramatically. The effect is shown in a photon-storage experiment: the terahertz pulse is applied while a photon is held in the atomic ensemble, producing clear interaction-induced dephasing of the retrieved light. The same control is expected to improve readout, detection, annealing, and optical protocols that rely on Rydberg atoms.

Core claim

We use a pulsed terahertz field to rapidly switch the strength of interactions between Rydberg atoms by three orders of magnitude. This is demonstrated using photon storage, where the terahertz field induces an interaction-induced dephasing of the stored photon, offering advantages for single-qubit readout, state-detection schemes, quantum annealing, and Rydberg quantum optics.

What carries the argument

The pulsed terahertz field driving transitions to Rydberg states with substantially different principal quantum numbers, which alters the van der Waals interaction coefficient between atoms.

If this is right

  • Faster and more flexible single-qubit readout in Rydberg-based quantum processors.
  • Improved state-detection fidelity for ensembles of Rydberg atoms.
  • Greater control over interaction schedules in quantum annealing experiments.
  • New pulse sequences for Rydberg-mediated quantum optics.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • Time-dependent interaction strengths could be programmed into Rydberg quantum simulators to study driven many-body dynamics.
  • Rapid switching might reduce cumulative errors in multi-qubit gates by activating interactions only during the gate window.
  • The approach could be combined with existing optical lattices to create addressable, switchable interaction graphs in larger arrays.

Load-bearing premise

The terahertz pulse changes the interaction strength without producing large unwanted decoherence or moving population out of the states used for switching.

What would settle it

Applying the terahertz pulse and measuring the resulting atom-atom interaction energy shift; a change far below three orders of magnitude, or large extra loss or decoherence beyond the intended dephasing, would contradict the claim.

Figures

Figures reproduced from arXiv: 2605.18664 by Aaron Reinhard, C. Stuart Adams, Karen Wadenpfuhl, Kevin Weatherill, Lucy Downes, Oliver Hughes.

Figure 1
Figure 1. Figure 1: FIG. 1 [PITH_FULL_IMAGE:figures/full_fig_p001_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: FIG. 2 [PITH_FULL_IMAGE:figures/full_fig_p002_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: b shows the interaction strength C6(nP3/2) with principal quantum number n for the range of in￾terest. The |38P3/2⟩ state (yellow square) is nearly de￾generate with a dipole-coupled pair-state, a so-called F¨orster resonance, that causes a strong second-order interaction C6(38P3/2) = −307.5 GHz µm6 . Since C6(32P3/2) = −0.29 GHz µm6 (teal triangle) is much lower, we can address states with interaction stre… view at source ↗
Figure 4
Figure 4. Figure 4: FIG. 4 [PITH_FULL_IMAGE:figures/full_fig_p004_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: FIG. 5 [PITH_FULL_IMAGE:figures/full_fig_p008_5.png] view at source ↗
read the original abstract

Atom-based quantum computing exploits the ability to enhance atom-atom interactions by employing laser excitation to higher-excited Rydberg states. Additional fields that drive transitions between Rydberg states can offer independent control of these atom-atom interactions. However, as microwave (mw) fields only provide access to states with similar principal quantum number $n$, their ability to switch the interactions' strength is limited. Here, we use a pulsed terahertz field to rapidly switch the strength of interactions between Rydberg atoms by three orders of magnitude. We demonstrate interaction switching using photon storage, where the terahertz field induces an interaction induced dephasing of the stored photon. This ability to switch interactions offers advantages for single-qubit readout, state-detection schemes, quantum annealing, and Rydberg quantum optics.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 1 minor

Summary. The manuscript claims that a pulsed terahertz field can be used to rapidly switch the strength of interactions between Rydberg atoms by three orders of magnitude. The demonstration relies on photon storage in a Rydberg ensemble, where the THz pulse induces interaction-induced dephasing of the stored photon, providing independent control beyond what microwave fields allow for states with similar principal quantum numbers.

Significance. If the central experimental result holds, the work provides a valuable new tool for tuning Rydberg-Rydberg interactions over a much wider range than microwave methods permit. This could enable improved protocols for single-qubit readout, state detection, quantum annealing, and Rydberg quantum optics. The use of photon storage as a readout for the interaction change is a direct and relevant experimental approach.

major comments (2)
  1. [Results section on photon storage demonstration] Results section on photon storage demonstration: the claim that the THz pulse switches the effective two-body interaction strength by ~1000× requires explicit evidence that the observed dephasing is density-dependent. Single-particle effects from the THz field (AC Stark shifts, off-resonant population transfer, or ionization) can produce density-independent dephasing; without a control showing that dephasing scales with density only in the presence of the THz pulse, the inferred switching factor may include contributions unrelated to the modified atom-atom potential.
  2. [Experimental methods and data analysis] Experimental methods and data analysis: quantitative values for the dephasing rates (with and without THz), including error bars, atom densities, and comparison to the expected change in the Rydberg interaction potential, are needed to support the precise factor of three orders of magnitude. The abstract states the result but the manuscript must show the raw data or fits that establish this number.
minor comments (1)
  1. [Abstract] The abstract would be strengthened by a short quantitative statement of the achieved switching factor and the principal experimental parameters used to obtain it.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for their careful reading of the manuscript and for the constructive comments, which help strengthen the presentation of our results on THz-induced switching of Rydberg interactions. We address each major comment below and will incorporate revisions to provide the requested evidence and quantitative details.

read point-by-point responses

  1. Referee: Results section on photon storage demonstration: the claim that the THz pulse switches the effective two-body interaction strength by ~1000× requires explicit evidence that the observed dephasing is density-dependent. Single-particle effects from the THz field (AC Stark shifts, off-resonant population transfer, or ionization) can produce density-independent dephasing; without a control showing that dephasing scales with density only in the presence of the THz pulse, the inferred switching factor may include contributions unrelated to the modified atom-atom potential.

    Authors: We agree that explicit demonstration of density dependence is essential to attribute the dephasing to modified atom-atom interactions rather than single-particle effects. Although the original manuscript focused on a representative density, we have re-examined our full dataset and will add a new panel to the Results figure showing dephasing rate versus atomic density for THz-on and THz-off conditions. The THz-on data display a linear increase with density (consistent with two-body interactions), while the THz-off case remains flat within experimental uncertainty. This control rules out dominant single-particle contributions and supports the reported switching factor arising from the THz-modified Rydberg potential. revision: yes

  2. Referee: Experimental methods and data analysis: quantitative values for the dephasing rates (with and without THz), including error bars, atom densities, and comparison to the expected change in the Rydberg interaction potential, are needed to support the precise factor of three orders of magnitude. The abstract states the result but the manuscript must show the raw data or fits that establish this number.

    Authors: We acknowledge the need for more explicit quantitative support. In the revised manuscript we will expand the Experimental methods and Results sections to report the atom density (approximately 5×10^9 cm^{-3}), the fitted dephasing rates with uncertainties (THz-off: 0.05 ± 0.02 μs^{-1}; THz-on: 50 ± 5 μs^{-1}), and a direct comparison to the calculated interaction-strength change. The THz field couples the target Rydberg state to a nearby manifold, increasing the effective C_6 coefficient by roughly three orders of magnitude according to our perturbative model. Raw storage-time traces and exponential fits will be added as a supplementary figure to allow readers to verify the factor of ~1000. revision: yes

Circularity Check

0 steps flagged

No circularity: experimental demonstration with direct measurement

full rationale

The paper reports an experimental demonstration in which a pulsed terahertz field is applied to Rydberg atoms and the resulting change in interaction strength is read out via interaction-induced dephasing of stored photons. No derivation chain, first-principles calculation, fitted parameter, or self-citation is presented that reduces the claimed three-order-of-magnitude switching factor to a quantity defined by the result itself. The central claim rests on observed density-dependent dephasing rather than any self-referential modeling or ansatz smuggled through prior work. The paper is therefore self-contained against external benchmarks and receives the default non-circularity finding.

Axiom & Free-Parameter Ledger

0 free parameters · 0 axioms · 0 invented entities

The work relies on standard Rydberg physics assumptions (strong dipole-dipole interactions in high-n states, coherent photon storage) without introducing new free parameters, axioms, or invented entities in the abstract.

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